How serious is listeriosis?

I have heard about listeriosis on the news. How serious is this illness?

Listeriosis is an uncommon illness caused by eating food contaminated by bacteria called Listeria monocytogenes. The bacteria lives in soil and water and is spread to fruit and vegetables growing in the soil. Many people carry the disease without experiencing any symptoms. Animals can also carry the bacteria. Soft cheeses, cold cuts, and other processed foods can be contaminated even after processing. Milk that is not pasteurized may be contaminated with the bacteria.

Pregnant women and their unborn infant, newborn babies, and adults with weak immune systems are most commonly infected. Listeriosis can cause premature birth, serious illness of the newborn, or stillbirth. Pregnant women infected with listeriosis may have only mild flu-like symptoms but their unborn child remains in serious danger. Sometimes healthy adults and children are infected but usually do not become seriously ill.

Listeriosis can be fatal. The symptoms of listeriosis begin suddenly and can include fever, aching muscles, nausea, diarrhea, cramps, and severe headache and usually start one day after eating contaminated food. The infection becomes more serious when it spreads to the nervous system causing infection of the brain and surrounding tissues. This is called meningitis or encephalitis. Listeriosis may cause a life-threatening infection of the blood called septicemia. More serious infections develop about 90-days after eating contaminated food. Most people are not treated for mild illness. If you are healthy and not pregnant, your symptoms should go away within a few weeks. Many pregnant women are treated with antibiotics to prevent the unborn infant from developing the illness. People at risk of becoming very sick with listeriosis are commonly treated with antibiotics.

Listeriosis can be prevented by storing, preparing and cooking foods safely. Wash your hands before and after handling foods or using the bathroom. Wash fruits and vegetables. Surfaces and utensils used to prepare food should be thoroughly cleaned. Do not eat undercooked meats. Do not keep leftovers for more than 2-3 days, and reheat them to an internal temperature of 74oC (165oF) before eating them. Perishable foods should be refrigerated or frozen within two hours. Defrost foods in the refrigerator, cold water or in the microwave but not at room temperature. If you are not sure about the quality of food, throw it away.

For more information about listeriosis, or for available programs and services, contact Health Link Alberta where nurses are available 24-7 to provide health advice and information. Call 1-866-408-LINK (5465) or 780-408-LINK (Edmonton area) or 403-943-LINK (Calgary area).